But what about Donald Trump? And more specifically, what about his choice for attorney general, Sen. Jeff Sessions (R-Ala.)?

Sessions has called for more federal prosecutions of marijuana growers and businesses in states where it is legal. He said in April that it's important for the government to send a "message with clarity that good people don't smoke marijuana." He declared that "we need grownups in charge in Washington to say marijuana is not the kind of thing that ought to be legalized, it ought not to be minimized, that it's in fact a very real danger."

One of the major difficulties in the burgeoning pot industry has long been the federal government's ability to prosecute businesses that the states say are legal. Making Sessions the head of the agency in charge of federal law enforcement and prosecutions has many in the cannabis community quite concerned.

"I can tell you that Sen. Sessions' nomination has a lot of people honestly scared for their businesses," said Jason Thomas, a former detention officer and marshal's deputy in Colorado who volunteers for the group Law Enforcement Against Prohibition. "He could dramatically change the legalized industry, recreation or medical. He could task the Department of Justice, the DEA, and even the FBI to work on shutting down the industry."

Robert Capecchi, the director of federal policies at the Marijuana Policy Project, noted that Sessions would face at least one stumbling block: The Rohrabacher-Farr amendment to the annual appropriations bill (which has to be renewed annually) prohibits the Department of Justice and the DEA from using money to target or prosecute state-compliant medical marijuana businesses. But other than that hurdle, Capechhi said, the only thing standing between Sessions and a crusade against states' legal pot industries is "just DOJ policy." And policies are not laws. "There's nothing set in stone."

Capecchi, though, is holding out hope, noting that Trump had suggested on the campaign trail that he supported medical marijuana and the states' rights argument in favor of full legalization. "I think the business man in Mr. Trump can see if you go after these businesses you drive all this legal and regulated marijuana market back underground."

Michael Liszewski, the director of government affairs for Americans for Safe Access, however, isn't banking on Trump's campaign promises quite yet. "A lot of people are aware of the pretty good things that President-elect Trump has said about medical marijuana," he said, "but Trump has sometimes changed his mind on certain positions."

Liszewski noted that Sessions isn't even the only Cabinet nominee to be opposed to marijuana. "Tom Price being nominated to Health and Human Services? That's another medical marijuana opponent being nominated to the Cabinet," he said.

In addition to the Rohrabacher-Farr amendment and an August appeals court ruling directing the DOJ to abide by it, Obama's attorneys general have issued a number of guidances on enforcing federal marijuana laws in states where it is legal for recreational or medical use, including its 2013 decision not to sue Colorado and Washington for their legalization laws (which was accompanied by a guidance for U.S. attorneys on what kinds of prosecutions they could and should pursue in such states), its 2014 guidance to banks that they might be able to offer financial services to state-compliant cannabis businesses (which the industry deemed insufficient), and a series of memos to U.S. attorneys directing them to focus on the black market for marijuana.

But any of the guidances issued by the department under President Obama, to which Sessions stated his opposition, could simply be rescinded by a Sessions-led Justice Department. And the Rohrabacher-Farr amendment applies only to the medical marijuana industry, leaving the legal recreational industry in four (soon to be eight) states subject to renewed enforcement.

Liszewski fears that most Americans aren't aware that it wouldn't take much to drive the industry into and then under the ground. "They probably have the impression that things are moving towards legality and that it's an inevitable thing," he said. "In the '70s, a lot of people in the marijuana movement also thought [legalization] was inevitable," but the Reagan administration cracked down instead, and it's been a difficult road for many advocates, patients, and business people who want to operate legally.

"All these appointments that are being made by President-elect Trump could really throw all that progress away."